The metabolism and distribution of 2,4,5-trichlorophenoxyacetic acid in female rats

1-¹⁴C]-2,4,5-Trichlorophenoxyacetic acid (2,4,5-T) was fed to pregnant and non-pregnant female rats at various dosages, and expired air, urine, feces, internal organs and tissues were analyzed for radioactivity. During the first 24 hr, 75 ± 7% of the radioactivity was excreted in the urine and 8.2 ± 4.6% in the feces. No ¹⁴C was found in the expired air. There was no significant difference in the rate of elimination between the pregnant and nonpregnant rats, or among the dosages used. Radioactivity was detected in all tissues, with the highest concentration being found in the kidney. The maximum concentration of radioactivity in all tissues was generally reached between 6 to 12 hr after po dosing and then started to decline rapidly. Radioactivity was also detected in the fetuses and in the milk. The average biological half-life of 2,4,5-T in the organs was 3.4 hr for the adult rats and 97 hr for the newborn.